1. Field of the Invention
The present invention relates to an electrochemical device including a pair of electrodes at least containing activated carbon powder, a separator interposed between the pair of electrodes, and an electrolytic solution impregnated into the pair of electrodes and the separator, the electrodes and the separator are stacked on a collector.
2. Description of the Related Art
An electric double layer capacitor has been conventionally used in a back-up power supply, an auxiliary power supply and the like, for a cellular telephone and a home appliance as a small-size high-capacity capacitor. A higher performance of such a capacitor has been expected.
A layer of electrodes made of activated carbon powder having uniform average grain sizes are used in this electric double layer capacitor (see FIG. 1). Moreover, to enhance a discharge capacity of the electric double layer capacitor, there is an attempt to increase a bulk density of the activated carbon powder included in the electrodes.
However, when increasing the bulk density of the electrodes, impregnation of an electrolytic solution into the electrodes is deteriorated. Also, incorporation of bubble and impregnation of the electrolytic solution into the electrodes are insufficient. Accordingly, there is a problem that the internal resistance increases after assembly.
To solve this problem, disclosed is a technique for impregnating the electrolytic solution into the electrodes for a long time, and for impregnating the electrolytic solution by evacuating it when infusing the electrolytic solution (see Japanese Unexamined Patent Publication No. Hei 5(1993)-343263, for example).